(-u² + 4u - 8) + (-u – 7) - (-8u² + 9u + 1)
To remove the parentheses put 1's just before them all
1(-u² + 4u - 8) + 1(-u – 7) - 1(-8u² + 9u + 1)
Then use the distributive law remembering to take the sign
+ or - along with 1 when multiplying through:
-u² + 4u - 8 - u - 7 + 8u² - 9u - 1
Combine the -u² with the +8u² and get 7u²
Combine the +4u, -u, and -9u as -6u
Combine the -8, the -7, and the -1 as -16
7u² - 6u - 16
If you like, you can factor that as
(7u + 8)(u - 2)
Edwin
AnlytcPhil@aol.com